|
|
Use of Marijuana in Neurological and Movement Disorders
1. What research has been done and what is known about the possible
medical uses of
marijuana?
There have been numerous studies both in animals and in various clinical
states on the use of
cannabinoids on neurological and various movement disorders. These results range
from
anecdotal reports to surveys and clinical trials. Marijuana or
tetrahydrocannabinol (THC) is
reported to have some antispasticity, analgesic, antitremor, and antiataxia
actions, as well as
some activity in multiple sclerosis (MS) and in spinal cord injury patients.
The spasticity and nocturnal spasms produced by MS and partial spinal cord
injury have been
reported to be relieved by smoked marijuana and to some extent by oral THC in
numerous
anecdotal reports. The effect seems to appear rapidly with smoked marijuana;
patients are able
to titrate the dose by the amount they smoke. No large-scale controlled studies
or studies to
compare either smoked or oral THC with other available therapies have been
reported. Several
relatively good therapeutic alternatives exist. There is no published evidence
that the cannabinoid
drugs are superior or even equivalent.
Substantial experimental animal literature exists showing that various
cannabinoids, given
primarily by parenteral routes, have a substantial anticonvulsant effect in the
control of various
models of epilepsy, especially generalized and partial tonic-clonic seizures.
Scant information is
available about the human experience with the use of marijuana or cannabinoids
for the treatment
of epilepsy. This is an area of potential value, especially for cannabis
therapies by other than the
smoked route.
Several single case histories have been reported indicating some benefit of
smoked marijuana for
dystonic states. It must be remembered that dystonia is a clinical syndrome with
numerous
potential causes, and the information available now does not differentiate which
causes are most
likely to be improved. Smoked marijuana and oral THC have been tested in the
treatment of
Parkinson's disease and Huntington's chorea without success.
The cannabinoids also have been used as experimental immunologic modifiers to
treat such
conditions as the animal models of experimental allergic encephalomyelitis (EAE)
and neuritis.
Parenteral cannabinoids have been successful in modifying EAE in animals,
suggesting that
cannabinoids may be of value in a more fundamental way by altering the root cause
of a disease
such as MS rather than simply treating its symptoms. Smoked marijuana would not
be acceptable
for such a role because of the variability of dose with the smoked route.
2. What are the major unanswered scientific questions?
The discovery of dedicated systems of central nervous system (CNS) neurons
approximately
8 years ago, which express receptors specific for the cannabinoids, is of major
scientific interest
and importance. The distribution of these cannabinoid receptor-bearing neurons
corresponds
well with the clinical effects of smoked marijuana; for instance, their presence
in the forebrain
may relate to adverse changes in short-term memory, but perhaps positively in the
control of
epilepsy. Cannabinoid receptors in the brainstem and cerebellum may relate to
the recognized
incoordination that accompanies smoked marijuana use. The discovery of intrinsic
ligands for
these receptors in the mammalian brain is also of great importance. This system
of cannabinoid
receptors and ligands may be analogous to the discovery of opiate receptors and
endorphins,
which linked various opium derivatives (heroin and morphine) to an intrinsic
system of neurons
in the CNS. That discovery was of major importance for pain research.
The major unanswered scientific questions are:
3. What are the diseases or conditions for which marijuana might have
potential as a treatment
and which merit further study?
Marijuana or the use of other cannabinoids as human therapies might be
considered for treating
spasticity and nocturnal spasms complicating MS and spinal cord injury, for
various active
epilepsy states, for some forms of dystonia, and perhaps most interestingly, for
treating
neuropathic pain (Zeltser et al. 1991). (Also see the chapter titled Analgesia.)
Neuropathic
pain complicates many CNS diseases. Few available therapies provide even partial
relief.
Reference
Zeltser, R.; Seltzer, Z.; Eisen, A.; Feigenbaum, J.J.; and Mechoulam, R. Suppression of neuropathic pain behavior in rats by a non-psychotropic synthetic cannabinoid with NMDA receptor-blocking properties. Pain 47(1):95-103, October 1991.
Go to the Medical Marijuana Menu
Go to the HIV & Nutrition Menu
Go to the HIVpositive.us Main Menu